The present invention relates to a granular detergent composition having easy measurability and distributivity suitable for use with a spoon.
The compactification of the powder detergent starting from 1987 has been popularized globe-wide within a short period of time, because the compactification has brought about great merits such as dramatic improvements in convenience of the users together with measuring method with spoons, and improvement of transportation efficiency and reduction of volume of space occupied in distributions and homes.
The technique for compactifying the powder detergent has been intensively studied in the recent years, but the main object of the problem of the technique is xe2x80x9chow to compactify powder detergent.xe2x80x9d In other words, the studies on improving the powder properties in compact detergents are remarked on solving problems such as caking property caused by compactification and suitability upon production, which are solutions for negative problems. Therefore, almost no attempts have been made for improving users"" feel or convenience of the consumers by remarkably improving the powder properties of the granular detergent composition, which is a proposal of positive value.
For instance, in conventional powder detergents, in the scooping movements with a spoon, since the stress from the detergent becomes large as the detergent is packed in the scooping portion of the spoon, the carton undesirably moves when this operation is carried out single-handedly, so that there arise problems that the detergent is not easily scooped, and that the detergent is undesirably spilled from the carton.
In addition, in the movement for spoon measurement after scooping, it has been difficult to level the detergent to a measurement scale owing to the fact that the cascading of the detergent particles from the spoon is discontinuous, for instance, the detergent particles suddenly flow downwards after tilting the spoon to get to a certain point, and the like. Moreover, it has been difficult to carry out an accurate measurement, because the packing structure of the detergent particles in the scooping portion of the spoon changes by repeatedly carrying out scooping movements in order to level the detergent to a given measurement scale.
Further, when the detergent is supplied into a washing machine, those detergents in which the cascading of the detergent particles is discontinuous are highly likely to be supplied as a lumpy mass. As a result, when a detergent is supplied before pouring water, and further washing is carried out at a low liquor ratio with gentle agitation, there arise problems such that the detergent is aggregated when pouring water at which point no mechanical power is applied, and further that the detergent aggregate does not sufficiently distribute owing to a gentle agitation force, so that there is likely to cause inconvenience that water-insoluble inorganic compounds remain on clothes.
In a high-density granular detergent composition, in order to conveniently carry out the operations of measuring the high-density granular detergent composition using a spoon-shaped measuring device, and supplying the granular detergent composition into a washing machine, it is desired that the granular detergent composition is easily scoopable, and that the granular detergent composition can be easily leveled to a desired measurement scale (hereinafter referred to as xe2x80x9ceasy measuringxe2x80x9d). In addition, in order to reduce the troubles that the water-insoluble inorganic compounds remain on clothes, it is desired that the granular detergent composition is easily evenly distributed when the detergent is supplied to a washing machine (hereinafter referred to as xe2x80x9ceasy distributingxe2x80x9d). Further, smooth powdery texture powder is pleasant for users.
Therefore, the present invention provides a high-density granular detergent composition having easy measurability and distributivity suitable for use with spoon measurement, and having high users"" feel of the consumers, and a process for preparing the granular detergent composition, in which the powder properties of the granular detergent composition are remarkably improved, so that the remnants of the granular detergent composition on clothes after washing are remarkably reduced because the granular detergent composition is less likely to be supplied as a lumpy mass, and that the users can easily carry out measurement operation of a detergent using a measuring device such as spoon.
For the purpose of obtaining a granular detergent composition having all of easy scooping, easy measuring and easy distributing, the present inventors have examined easy scooping with a spoon, and easy measuring and easy distributing for 100 or more samples in which the powder properties of the granular detergent composition such as a time period for flowability, a bulk density, an average particles size, a particle size distribution, a fine powder ratio, a degree of spherocity, and a tensile strength of a powder layer are variously changed.
As a result, it has been elucidated that it would be quite difficult to achieve the problem solving of the present invention by simply optimizing the conventionally used index for flowability, such as a time period (flow time) required for flowing a given amount of the granular detergent composition from a hopper used in a measurement of bulk density according to JIS K 3362. This is because these flowability indexes simply express powder properties within a given time period from a start of flow to an end of flow of powder, and cannot express changes of complicated flowability behaviors of the granular detergent composition which vary with time within a second time period, and the like.
Therefore, while the present inventors have proceeded with data analysis for previously obtained various detergent samples, they have analyzed in detail the movements of users from measurement to supply of the detergent, such as xe2x80x9cscooping,xe2x80x9d xe2x80x9cmeasuring,xe2x80x9d and xe2x80x9cdistributing.xe2x80x9d As a result, they have newly achieved introduction of powder property indexes more closely adapting to the actual situation, including an inserting pressure (P) as an index for expressing easy scooping, a xcex94 dropping ratio (D) as an index for easy measuring, and a variance of powder dropping rate (V) as an index for expressing easy distributing.
Therefore, first, they have examined the relationship between the variance of powder dropping rate (V), which is an index for expressing easy distributing, and the property of insoluble remnants of the granular detergent composition, and found conditions that can reduce the generation of the insoluble remnants of the granular detergent composition by adjusting the variance of powder dropping rate (V) to a given value or less.
Subsequently, in order to obtain conditions for having both easy scooping and easy measuring, in addition to the above easy distributing, the studies have been continued by varying operating factors drawn on two axes of the inserting pressure (P) as an index for expressing easy scooping and the xcex94 dropping ratio (D) as that for easy measuring. As a result, it has been found that it is important that both the inserting pressure (P) and the xcex94 dropping ratio (D) are small, and when both factors have the relationship within a specified range (index K), a realistic solving means for the above problems can be provided.
As a result, the present inventors have found that a granular detergent composition having easy measurability and distributivity suitable for spoon measurement, the granular detergent composition having convenience not conventionally found and smooth powdery texture not so far found, which can also express its commercial value as xe2x80x9ccapable of scooping single-handedly without spilling, with a single-step measurement, and with reduced insoluble remnants.xe2x80x9d
In addition, they studied on a process for preparation for the granular detergent composition having easy measurability and distributivity suitable for spoon measurement. As a result, it has been elucidated that in the preparation of the granular detergent composition, the control of each of the operation factors of the present invention, the variance of powder dropping rate (V), the inserting pressure (P), and the xcex94 dropping ratio (D), can be achieved by carrying out the adjustment operations for the powder properties comprising the particle size adjustment, the particle shape adjustment and the adjustment of intergranular cohesive forces.
In particular, by adjusting each of adjustment factors such as the average particle size of the granular detergent composition, the particle size distribution (Rosin-Rammler""s distribution index), the fine powder ratio having a particle size of 125 xcexcm or less, the degree of spherocity, the tensile strength of the powder layer to preferable operation ranges which minimally meet the requirement, and further by especially adjusting two or more selected from the above-mentioned items, they have found that a granular detergent composition having easy measurability and distributivity suitable for desired spoon measurement is extremely easily obtained, and the present invention has been perfected thereby.
Specifically, the present invention relates to:
[1] a granular detergent composition having easy measurability and distributivity suitable for spoon measurement, a bulk density thereof being 500 g/L or more, comprising a surfactant, a water-insoluble inorganic compound and a water-soluble salt, wherein the granular detergent composition has a variance of powder dropping rate V of 1.0 or less, an inserting pressure P of 80 gf/cm or less, a xcex94 dropping ratio D of 14% or less, and an index K of from 30 to 230, the index K being represented by the equation (1):
K=Pxc3x97exp(0.135xc3x97D)xe2x80x83xe2x80x83(1)
xe2x80x83wherein P stands for an inserting pressure (gf/cm), and D stands for a xcex94 dropping ratio (%); and
[2] a process for preparing a granular detergent composition having easy measurability and distributivity suitable for spoon measurement, a bulk density thereof being 500 g/L or more, comprising a surfactant, a water-insoluble inorganic compound and a water-soluble salt, wherein the process comprises carrying out a particle size adjustment, a granular shape adjustment and an adjustment of intergranular cohesive forces such that detergent particles constituting the granular detergent composition have a variance of powder dropping rate V of 1.0 or less, an inserting pressure P of 80 gf/cm or less, a xcex94 dropping ratio D of 14% or less, and an index K of from 30 to 230, the index K being represented by the equation (1) as defined in item [1] above.